Differential proteome analysis of colon carcinoma cell line SW480 after reconstitution of the tumour suppressor Smad4

miR-1307-3p overexpression inhibits cell proliferation and promotes cell apoptosis by targeting ISM1 in colon cancer

BACKGROUND

colon adenocarcinoma (COAD) is the most common malignant tumor of gastrointestinal tract. Our study attempts to explore the effect of miR-1307-3p on biological function of COAD cells and its connection with isthmin 1 (ISM1).

METHODS

The miRNA dataset and clinical information of patients with COAD were downloaded from The Cancer Genome Atlas (TCGA) database. The survival prognosis was analyzed by GGSURV package from R. MicroRNA (miR)-1307-3p was identified by identifying overlapping miRNAs that target ISM1, across two databases (miRDB and Targetscan). Dual luciferase reporter assay was employed to scrutinize the relationship between miR-1307-3p and ISM1. RT-PCR was used to quantify miR-1307-3p and ISM1 expression of colon cancer tissues and cell lines. Western blot was performed to quantify related protein expression. Flow Cytometry, CCK8 and colony formation assays were performed to evaluate the apoptosis, cell cycle, cell viability and proliferation of COAD cells.

RESULTS

miR-1307-3p mRNA level decreased in both COAD tissues and cell lines. Overexpression of miR-1307-3p suppressed the proliferation, promoted apoptosis and arrested cell cycle at G1 phase, meanwhile, downregulation of ISM1 accelerated the proliferation, inhibited apoptosis and promote cell cycleprogression. The result of dual luciferase reporter assay indicated that miR-1307-3p targeted ISM1 directly and inhibited its expression. The functions of miR-1307-3p regulating cleaved caspase-3, cyclinD1, Ki67 protein levels and activation of Wnt3a/β-catenin signaling pathway were reversed by ISM1.

CONCLUSIONS

miR-1307-3p inhibited activation of Wnt3a/β-catenin signaling through targeting downregulation of ISM1, thereby inhibited proliferation and promote apoptosis of COAD cells.

Roles of Smads Family and Alternative Splicing Variants of Smad4 in Different Cancers

Transforming Growth Factor β (TGF-β) is one of the most common secretory proteins which are recognized by membrane receptors joined to transcription regulatory factor. TGF-β signals are transduced by the Smads family that regulate differentiation, proliferation, early growth, apoptosis, homeostasis, and tumor development. Functional study of TGF-β signaling pathway and Smads role is vital for certain diseases such as cancer. Alternative splicing produces a diverse range of protein isoforms with unique function and the ability to react differently with various pharmaceutical products. This review organizes to describe the general study of Smads family, the process of alternative splicing, the general aspect of alternative splicing of Smad4 in cancer and the possible use of spliceoforms for the diagnosis and therapeutic purpose. The main aim and objective of this article are to highlight some particular mechanisms involving in alternatives splicing of cancer and also to demonstrate new evidence about alternative splicing in different steps given cancer initiation and progression.

Contribution of proteomics to the study of the role of cytokeratins in disease and physiopathology

Cytokeratins (CKs), the most abundant group of cytoskeletal intermediate filaments, and proteomics are strongly connected. On the one hand, proteomics has been extremely useful to uncover new features and functions of CKs, on the other, the highly abundant CKs serve as an exceptional tool to test new technological developments in proteomics. As a result, proteomics has contributed to finding valuable associations of CKs with diseases as diverse as cancer, cystic fibrosis, steatohepatitis, viral and bacterial infection, keratoconus, vitreoretinopathy, preeclampsia or the chronic fatigue syndrome, as well as to characterizing their participation in a number of physiopathological processes, including drug resistance, response to toxicants, inflammation, stem cell differentiation, embryo development, and tissue repair. In some cases, like in cystic fibrosis, CKs have been described as potential therapeutic targets. The development of a specific field of proteomics where CKs become the main subject of research aims and hypotheses is suggested.

Repression of KIAA1199 attenuates Wnt-signalling and decreases the proliferation of colon cancer cells

BACKGROUND

The KIAA1199 transcript is upregulated in colon adenomas and downregulated upon β-catenin knockdown.

METHODS

Transcript profiling was performed on >500 colon biopsies, methylation profiling data were compared with transcript data. Immunohistochemistry assessed KIAA1199 protein expression in 270 stage II/III tumours (>3 years follow-up). The effects of stable KIAA1199 knockdown in SW480 cells (three different constructs) were studied using transcriptional profiling, proliferation and protein analysis.

RESULTS

The KIAA1199 transcript was strongly upregulated in 95% of adenocarcinomas. Absent expression in normal mucosa correlated with KIAA1199 promotor methylation. Nuclear and cytoplasmic KIAA1199 protein expression was identified in colon adenocarcinomas and other types of cancers. A subpopulation of patients with tumours strongly expressing KIAA1199 in the nucleus showed a better outcome with regard to recurrence as lung or liver metastases. The KIAA1199 knockdown affected the cell cycle and the Wnt-signalling pathway. Reduced cellular proliferation and decreased KI67, phosphorylated retinoblastoma, β-catenin and ASCL2 protein expression supported these findings. Eighteen Wnt-signalling genes differentially expressed upon KIAA1199 knockdown correlated with the KIAA1199 expression profile in clinical specimens.

CONCLUSION

The KIAA1199 knockdown attenuates the effects of the Wnt/β-catenin signalling and it may thus be regarded as a regulatory part of this pathway.

Application of proteomics in colorectal cancer research

Colorectal cancer is one of the most common malignant tumors in China. Its morbidity and mortality are increasing year by year. The emergence of proteomics has pushed colorectal cancer research forward. In this article, we will review the application of proteomics in the study of the diagnosis, pathogenesis and treatment of colorectal cancer.

Phosphoprotein Keratin 23 accumulates in MSS but not MSI colon cancers in vivo and impacts viability and proliferation in vitro

Transcript profiling of 27 normal colon mucosas and 258 adenocarcinomas showed Keratin23 to be increased in 78% microsatellite-stable tumors, while microsatellite-instable tumors showed low transcript levels, comparable to normal mucosas. Immunohistochemical analyses demonstrated that 88% of microsatellite-instable tumors were negative for Keratin23 protein, while 70% of MSS tumors and metastases derived from MSS-tumors showed high Keratin23 levels. Immunofluorescence analysis localized Keratin23 in the Golgi-apparatus. Golgi accumulation was unique for gastrointestinal adenocarcinomas. Immunoprecipitation and 2D-blot analysis revealed Keratin23 to be a 46.8 kDa phosphoprotein. Keratin23 impaired the proliferation of human colon cancer cells significantly, leading to cell death in microsatellite-instable but not microsatellite-stable cell lines, while COS7 cells experienced multiple nuclei and apoptosis. Keratin23 expression correlated significantly with transcription factor CEBPB. In conclusion, Keratin23 expression is a novel and important difference between microsatellite-stable and microsatellite-instable colon cancers.